This prompt is for integration engineers and backend developers who receive model-generated API payloads that violate the expected envelope structure. The core job-to-be-done is correcting malformed HTTP response wrappers—such as a missing top-level data key, an incorrect status field, or a wrong Content-Type—before the payload is returned to a client or processed by downstream services. The ideal user is someone who already has a valid OpenAPI or GraphQL schema and needs the model to self-correct its output to match that contract, using few-shot examples of the correct envelope pattern.
Prompt
API Response Wrapping Fix Prompt

When to Use This Prompt
Define the job, reader, and constraints for the API Response Wrapping Fix Prompt.
Use this prompt when the model consistently produces structurally invalid API responses that fail client-side parsing or middleware validation. It is most effective when the semantic content inside the payload is correct but the wrapper is wrong—for example, the model returns { "user": {...} } instead of { "data": { "user": {...} }, "status": 200 }. The prompt relies on providing the target schema and concrete wrapping/unwrapping examples. Do not use this prompt to fix deeply nested semantic errors, business logic violations, or authorization issues; those require different repair strategies. You must supply the expected envelope schema as part of [CONTEXT] and at least two contrasting examples in [EXAMPLES]—one showing the malformed input and the corrected output, and another showing a correctly wrapped response for reinforcement.
Before wiring this into a production pipeline, define a validation step that checks the repaired output against your API contract using a schema validator. If the repair fails validation, escalate to a retry with a more explicit error message or route to a human reviewer for schema-level failures. Avoid using this prompt as a permanent fix; if wrapping errors are frequent, revisit the upstream system prompt or model choice. The next step is to copy the prompt template and adapt the [SCHEMA] and [EXAMPLES] placeholders to match your specific API envelope.
Use Case Fit
Where the API Response Wrapping Fix Prompt delivers value and where it introduces risk. Use these cards to decide if this pattern fits your integration pipeline.
Good Fit: Post-Processing Unreliable LLM Output
Use when: Your model consistently generates correct payloads but wraps them in conversational text, extra markdown fences, or omits required envelope fields like statusCode or headers. Guardrail: Apply this prompt as a targeted repair step after initial generation, not as a replacement for schema-constrained generation.
Bad Fit: Real-Time Streaming Responses
Avoid when: You need to fix wrapping errors in streaming chunks where the full response body isn't available yet. Guardrail: For streaming, enforce the correct envelope structure at the application layer before sending the first chunk, and use this prompt only for non-streaming fallback or log analysis.
Required Input: Valid API Contract
Risk: Without a concrete OpenAPI spec, GraphQL schema, or expected response shape, the model may normalize to an incorrect or outdated envelope. Guardrail: Always provide the target schema as part of [CONTEXT] and validate the repaired output against it programmatically before returning to the client.
Required Input: Diverse Few-Shot Examples
Risk: A single wrapping example causes the model to overfit to that specific structure, failing on edge cases like error responses or paginated envelopes. Guardrail: Include at least 3-5 examples covering success, error, empty, and paginated response shapes to teach the general wrapping pattern.
Operational Risk: Silent Content Mutation
Risk: The repair prompt might silently drop fields, reorder keys, or coerce types in ways that break downstream consumers. Guardrail: Run a structural diff between the raw output and the repaired output, logging any field removals or type changes for human review before the repair is accepted.
Operational Risk: Repair Loop Amplification
Risk: If the repair prompt itself produces invalid output, you can enter a costly retry loop where each repair attempt consumes tokens without converging. Guardrail: Set a maximum of 2 repair attempts, then escalate to a human operator or fall back to a static default error envelope.
Copy-Ready Prompt Template
A reusable prompt template for fixing API response wrapping errors using few-shot corrective examples.
This template provides a production-ready prompt for repairing model-generated API responses that violate the expected envelope structure. It is designed for integration engineers who need to correct malformed JSON payloads—such as missing status fields, incorrect Content-Type headers, or wrong top-level keys—before the response reaches a client or downstream service. The prompt uses few-shot examples to demonstrate the correct wrapping pattern, making it more reliable than instruction-only approaches for complex nested schemas.
textYou are an API response repair system. Your job is to take a malformed API response and rewrite it to match the expected envelope structure defined by the target API specification. [API_SPECIFICATION] [EXAMPLES] ## Instructions 1. Analyze the [INPUT] response against the specification above. 2. Identify all structural violations: missing or extra top-level keys, incorrect status fields, wrong content types, or malformed data payloads. 3. Apply the corrections demonstrated in the examples. 4. If the data payload itself is valid but wrapped incorrectly, preserve the payload content and fix only the envelope. 5. If the data payload is also malformed, flag it with a `"repair_note"` field in the corrected response. 6. Output ONLY the corrected JSON response. Do not include explanations, markdown fences, or commentary. [INPUT]
Adaptation guidance: Replace [API_SPECIFICATION] with a concise description of the expected envelope, such as {"status": "success|error", "data": {...}, "meta": {"timestamp": "ISO8601"}}. Populate [EXAMPLES] with 3–5 input-output pairs showing common wrapping errors and their corrections. The [INPUT] placeholder should receive the raw, malformed model output at runtime. For high-risk APIs (payments, health data), add a [CONSTRAINTS] block requiring human review when the repair confidence is low or when the data payload itself is altered. Always validate the corrected output against the target schema before returning it to the client.
Prompt Variables
Required inputs for the API Response Wrapping Fix Prompt. Each placeholder must be populated before the prompt is assembled and sent. Validation notes describe how to check the input before execution.
| Placeholder | Purpose | Example | Validation Notes |
|---|---|---|---|
[RAW_MODEL_OUTPUT] | The malformed API response string produced by the model that needs wrapping repair | {"data": {"id": 1}} | Must be a non-empty string. Check that it contains parseable fragments of JSON, XML, or GraphQL. If empty or null, skip the repair prompt and return an error to the caller. |
[TARGET_SCHEMA] | The expected API envelope schema the output must conform to, expressed as an OpenAPI response object or GraphQL type definition | {"type": "object", "required": ["status", "data"], "properties": {"status": {"type": "integer"}, "data": {"type": "object"}}} | Must be a valid JSON Schema or GraphQL SDL snippet. Validate with a schema parser before injection. If the schema is malformed, the repair prompt will produce unreliable output. |
[CONTENT_TYPE] | The expected content type header or media type for the response | application/json | Must be a valid IANA media type string. Common values: application/json, application/xml, application/graphql+json. If missing, default to application/json and log a warning. |
[STATUS_FIELD_REQUIRED] | Boolean indicating whether a top-level status code or success field is mandatory in the envelope | Must be true or false. If true, the repair prompt will inject a missing status field. If false, the prompt will skip status injection. Validate as a strict boolean before template insertion. | |
[ERROR_WRAPPING_EXAMPLE] | A concrete example showing the correct error envelope structure for this API | {"status": 400, "error": {"code": "INVALID_INPUT", "message": "Missing required field"}} | Must be a valid JSON object matching the TARGET_SCHEMA error shape. If the API has no error envelope, set to null. Validate structural match against the schema's error definition. |
[SUCCESS_WRAPPING_EXAMPLE] | A concrete example showing the correct success envelope structure for this API | {"status": 200, "data": {"id": "123", "name": "Example"}} | Must be a valid JSON object matching the TARGET_SCHEMA success shape. Validate structural match against the schema's success definition. This example is used as the primary few-shot demonstration. |
[UNWRAPPING_FLAG] | Boolean indicating whether the RAW_MODEL_OUTPUT is already wrapped incorrectly and needs unwrapping before re-wrapping | Must be true or false. If true, the prompt includes unwrapping instructions to strip an incorrect outer envelope. If false, the prompt assumes the raw output is the inner payload. Validate as a strict boolean. | |
[MAX_RETRY_DEPTH] | Integer specifying how many nested wrapping attempts are allowed before escalation | 3 | Must be a positive integer between 1 and 5. Used to prevent infinite repair loops. If the repair prompt itself produces malformed output, increment a counter and retry up to this limit before escalating to human review. |
Implementation Harness Notes
How to wire the API Response Wrapping Fix Prompt into a production application with validation, retries, and logging.
The API Response Wrapping Fix Prompt is designed to sit inside a repair loop that activates after your primary generation step produces a response that fails an envelope contract check. Do not call this prompt on every response—only when a lightweight structural validator (checking for the presence of data, errors, statusCode, or the expected GraphQL data/errors wrapper) returns a failure. This keeps latency and cost low for the 90%+ of responses that are already well-formed. The prompt expects the malformed raw output and the target API contract (OpenAPI response schema or GraphQL operation definition) as inputs, and it returns a corrected payload that should pass the same validator.
Integration flow: 1) Primary model generates a response. 2) A structural validator checks for the required envelope fields and content-type headers. 3) On failure, the raw output and the expected schema are passed to this repair prompt. 4) The repaired output is re-validated. 5) If it passes, return it to the caller; if it fails again, log the failure and either escalate to a human reviewer or return a controlled error response. Model choice: This repair task benefits from models with strong instruction-following and JSON manipulation capabilities. GPT-4o, Claude 3.5 Sonnet, and Gemini 1.5 Pro all perform well. Avoid smaller or older models (e.g., GPT-3.5-turbo) for nested envelope repairs, as they tend to hallucinate field values when restructuring. Validation: Use a deterministic post-repair validator that checks: (a) the top-level keys match the expected envelope, (b) required fields like statusCode or errors are present and of the correct type, (c) the Content-Type header or wrapper implies the right format (e.g., application/json), and (d) nested payloads parse correctly. Do not rely on the model's self-report of success.
Retries and failure modes: Set a maximum of 2 repair attempts. If the first repair fails validation, feed the validator's specific error message back into the prompt as additional context for a second attempt. If the second attempt also fails, stop retrying. Common failure modes include: the model inventing data to fill missing required fields (mitigate by instructing it to use null or explicit error markers), the model changing the semantic content of the payload while fixing the envelope (mitigate by diffing the pre-repair and post-repair inner payloads and flagging changes >5% for review), and the model wrapping an already-correct payload in a second envelope layer (mitigate by checking for double-wrapping in the validator). Logging: Log every repair invocation with the original output, the repair prompt used, the repaired output, the validation result, and the number of attempts. This data is essential for detecting prompt drift—if the repair rate suddenly increases, your primary prompt or model behavior has likely changed. Human review: For APIs in regulated domains (payments, healthcare, legal), route any twice-failed repair to a human review queue rather than returning a potentially malformed response to the end user. The repair prompt is a production safeguard, not a substitute for correct primary generation.
Expected Output Contract
Fields, types, and validation rules for the repaired API response envelope. Use this contract to validate the model's output before forwarding it to downstream consumers or retry logic.
| Field or Element | Type or Format | Required | Validation Rule |
|---|---|---|---|
response_envelope | object | Top-level key must exist and be a JSON object; reject if array, string, or null | |
response_envelope.status_code | integer (100-599) | Must be a valid HTTP status code; reject if missing, non-integer, or outside 100-599 range | |
response_envelope.headers | object | Must contain at minimum Content-Type; reject if missing or Content-Type is not a valid media type string | |
response_envelope.headers.Content-Type | string (MIME type) | Must match one of [application/json, application/xml, text/plain]; reject on mismatch or absence | |
response_envelope.body | object | array | string | null | Must be present; null allowed only for 204 No Content; reject if missing on non-204 status codes | |
response_envelope.body.data | object | array | If present, must match the expected schema shape from [API_SCHEMA]; reject on structural mismatch | |
response_envelope.body.error | object | If present, must contain code and message string fields; reject if malformed or missing required sub-fields | |
response_envelope.body.error.code | string | Must be a non-empty string when error object exists; reject if empty or missing | |
response_envelope.body.error.message | string | Must be a non-empty string when error object exists; reject if empty or missing |
Common Failure Modes
API response wrapping failures break downstream consumers silently. These are the most common structural failures and how to prevent them before they reach production.
Missing Envelope Fields
What to watch: Model omits required wrapper fields like status, metadata, pagination, or errors that API consumers expect. The payload is valid JSON but fails client-side deserialization. Guardrail: Include a complete envelope schema in the prompt with explicit required field annotations. Validate output against the OpenAPI or GraphQL schema before returning to the client.
Wrong Content-Type Structure
What to watch: Model generates a REST-style envelope for a GraphQL endpoint, or wraps a single object when the contract expects an array. The structure is internally consistent but matches the wrong API contract. Guardrail: Include the target API type and version in the system prompt. Use few-shot examples that show the exact envelope shape for each supported content type.
Nested Data Drift
What to watch: Model places response data at the wrong nesting level—response.data vs response.payload.result—or flattens nested objects that should remain structured. Guardrail: Provide a concrete output schema with explicit nesting paths. Add a post-processing validator that checks field paths exist at expected locations before client delivery.
Status Code Mismatch
What to watch: Model returns status: 'success' with error content, or status: 'error' with valid data. HTTP status codes and envelope status fields become inconsistent. Guardrail: Include few-shot counterexamples showing correct status-to-content mapping. Validate that error envelopes contain error details and success envelopes contain data before responding.
Collection vs. Singleton Confusion
What to watch: Model wraps a single object in an array when the contract expects a bare object, or returns a bare object when the contract expects a collection. List endpoints break pagination; detail endpoints break deserialization. Guardrail: Explicitly tag the endpoint type in the prompt context. Use schema validation that checks array vs. object type at the expected data path.
Pagination Metadata Omission
What to watch: Model returns correct data but drops total, page, next_cursor, or has_more fields. Clients can't paginate and either loop infinitely or miss data. Guardrail: Require pagination fields in the output schema even when values are unknown—use explicit null or placeholder markers. Validate pagination field presence before returning list responses.
Evaluation Rubric
Criteria for testing the API Response Wrapping Fix Prompt before deployment. Each row defines a pass standard, a failure signal, and a concrete test method.
| Criterion | Pass Standard | Failure Signal | Test Method |
|---|---|---|---|
Envelope Structure Correction | Output matches the target [WRAPPER_SCHEMA] with correct status, data, and error fields | Missing or extra top-level keys; data nested at wrong depth | Schema diff: compare output JSON structure against [WRAPPER_SCHEMA] using structural comparison, not value matching |
Status Field Injection | Missing status field is added with correct value derived from [INPUT_PAYLOAD] context | Status field still absent or assigned wrong value (e.g., 200 for error case) | Field presence check: assert 'status' in output; value check: assert status matches expected code from [EXPECTED_STATUS] |
Content-Type Header Correction | Content-Type field in envelope matches [TARGET_CONTENT_TYPE] exactly | Content-Type remains as original wrong value or is set to generic application/json | String equality check: assert output.content_type === [TARGET_CONTENT_TYPE] |
Nested Data Preservation | All original data fields from [INPUT_PAYLOAD] appear in correct envelope location without loss or corruption | Data fields missing, renamed, or moved to wrong nesting level | Deep equality on data subtree: extract data field from output, compare against [INPUT_PAYLOAD] data using recursive field-by-field match |
Error Envelope Handling | When [INPUT_PAYLOAD] contains error details, output uses error envelope structure with error.code and error.message fields | Error details placed in data field instead of error field; error structure missing required subfields | Schema validation: validate output against error sub-schema from [WRAPPER_SCHEMA]; assert error.code is non-null string |
GraphQL Response Wrapping | For GraphQL targets, output includes data and errors at top level per GraphQL spec, not REST-style envelope | GraphQL response wrapped in REST envelope with status field; errors array missing or malformed | Spec compliance check: assert output has keys 'data' and 'errors'; assert no 'status' or 'code' at top level when [TARGET_TYPE] is GraphQL |
Empty Payload Handling | Null or empty [INPUT_PAYLOAD] produces valid envelope with null data field and appropriate status, not broken structure | Output is empty string, parse error, or envelope with missing required fields | Null input test: provide null [INPUT_PAYLOAD]; assert JSON.parse succeeds; assert output matches empty-payload example from [FEW_SHOT_EXAMPLES] |
Malformed Input Recovery | Partially wrapped or double-wrapped [INPUT_PAYLOAD] is unwrapped and re-wrapped correctly without data duplication | Output contains nested wrappers, duplicate status fields, or data wrapped at wrong level | Unwrapping test: provide double-wrapped input; assert output has exactly one wrapper layer; assert inner data matches original unwrapped payload |
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Adapt This Prompt
How to adapt
Use the base prompt with a single example pair showing the malformed envelope and the corrected version. Skip schema validation in the prompt itself—rely on post-processing in application code. Keep the instruction short: "Fix the response wrapper to match this example."
Prompt snippet
codeFix the API response wrapper below so it matches the correct structure shown in the example. [INCORRECT_RESPONSE] Example correct structure: [CORRECT_EXAMPLE] Return only the corrected response.
Watch for
- Model may fix the wrapper but alter payload content
- No guard against hallucinated status codes
- Single example may overfit to one error pattern

About the author
Prasad Kumkar
CEO & MD, Inference Systems
Prasad Kumkar is the CEO & MD of Inference Systems and writes about AI systems architecture, LLM infrastructure, model serving, evaluation, and production deployment. Over 5+ years, he has worked across computer vision models, L5 autonomous vehicle systems, and LLM research, with a focus on taking complex AI ideas into real-world engineering systems.
His work and writing cover AI systems, large language models, AI agents, multimodal systems, autonomous systems, inference optimization, RAG, evaluation, and production AI engineering.
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